poisson_func <- function(x,beta0,beta1) {
theta <- exp(beta0 + beta1*x)
}
curve(poisson_func(x,0,1),xlim=c(-1,5), lwd=2,ylab="poisson_func function", las=1)
curve(poisson_func(x,-2,1),xlim=c(-1,5), lwd=2, lty=2, col="red", add=TRUE)
curve(poisson_func(x,2,1),xlim=c(-1,5), lwd=2, lty=2, col="blue", add=TRUE)
legend(-1,150,c(expression(paste(beta[0]," = 0")),
expression(paste(beta[0]," = -2")),
expression(paste(beta[0]," = 2"))),
lwd=2, lty=1:3, col=c("black","red","blue"))